1. Field of the Invention
The present invention relates to an ink jet recording head that creates ink liquid droplets used for ink jet recording. More particularly, the invention relates to an ink jet recording head obtainable by a method for stably forming an ink-supply through opening by means of Si anisotropic etching. The invention also relates to a method for manufacturing such head.
2. Related Background Art
Conventionally, it has been generally practiced to provide the ink-supply through opening for the substrate of an ink jet (hereinafter referred to as IJ) head of the so-called side shooter type where ink liquid droplets are discharged in the direction perpendicular to the surface of the substrate on which the ink discharge pressure generating elements are formed.
As a method of the kind, there are known the mechanical method for processing substrates by means of sand blasting, and the Si chemical etching method for processing them.
Particularly, the Si anisotropic etching is most preferably applicable to the method for forming the ink-supply through opening, because with this type of etching, the through opening can be formed in good precision.
With the ink supply port precisely formed, it becomes possible to shorten the distance between the ink supply port and the ink discharge pressure generating elements. As a result, the ink discharge frequency is significantly enhanced (see the specifications of U.S. Pat. No. 4,789,425, and EP 0609911A2).
However, when the through opening is formed by means of the anisotropic etching, abnormal etching may take place in some cases due to the defective Si crystals (such abnormal etching leads to the resultant variation of the widths of through openings thus formed to a considerable extent, because the planes other than the &lt;100&gt; plane are also etched with each defective crystal as its starting point). This is one of the factors that may cause the reduction of the production yield.
Further, when the Si anisotropic etching is performed, the starting time of etching may minutely vary depending on the state of the surface where the etching begins, as well as on the etching conditions (such as the concentration of etching solution, temperature, among some others). Therefore, there is a need for an overetching in order to complete the penetration for the formation of each ink supply port reliably.
However, with the overetching, there occurs the side etching on the Si wafer in the horizontal direction. As a result, the resultant width of each through opening varies minutely, leading to the drawback that the distance may vary between the ink supply port and the ink discharge pressure generating elements.